Methods of mixing impeller sensing

Abstract

A method is provided for monitoring a flow behavior of mixed components without requiring additional instrumentation or sampling. The method is carried out by determining ratios of the power required to rotate a mixing impeller at different rotational speeds and then comparing the ratios. Characteristics about the mixed components are determined based on differences between the ratios.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The invention relates to a method of monitoring a flow behaviour of components to be mixed, a control system and methods for detecting settled solids at a mixing impeller.[0003]2. Related Art[0004]Biopharmaceutical manufacturing requires mixing at several process steps, for example media preparation, buffer preparation, low pH viral inactivation of material between process steps. For this mixing step, usually the components to be mixed are accommodated in a mixing vessel in which a mixing impeller is provided. The mixing impeller is driven by a motor so that the mixing impeller is rotated. The mixing impeller usually comprises a rotationally symmetric mixing impeller basis and at least one mixing impeller blade that is attached to the mixing impeller basis. The mixing impeller blade extends radially or axially with respect to a rotation axis from the mixing impeller basis. The geometry and size of the mixing blade are chosen depending o...

AI Technical Summary

Benefits of technology

The described method uses a simple and inexpensive way to determine the density and viscosity of mixed components without needing further instrumentation or sampling. The method compensates for any variations in density that may occur during the mixing process. The speed of the mixing impeller can be reduced in steps and maintained for a specific time to allow for a stable flow pattern. The mixing impeller can also be moved in a direction perpendicular to its rotation axis to reduce the gap between the housing and the mounting depression. The detection of solids can prevent damage to the mixing impeller and mixing vessel by detecting blockages.

Problems solved by technology

However, some applications require that the mixing equipment is fully closed with no possibility of leakage between the mixing vessel and the environment—for example, the fluids to be mixed are either hazardous (e.g. toxic) or if they are sensitive to contamination from the outside environment (e.g. highly purified pharmaceutical material).

Although the solids are typically added to the liquid while the mixing impeller is rotating, there are situations in which the mixing impeller may be partially or fully obstructed by solid, like e.g. powder.

In this case, the mixing impeller is at least partly inoperable and damages may occur at the mixing impeller, the mixing vessel and / or the motor driving the mixing impeller.

Therefore, it is the underlying technical problem to provide a method for detecting solids at a mixing impeller which might block the mixing impeller and causes damages to the mixing system.

In the case that solids are settled into the space between the mixing impeller housing and the mounting depression, the resulting friction may prevent the mixing impeller from starting or it could generate particulate by grinding against the walls of the mixing impeller and the mounting depression.

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